The present invention relates to an automatic interior cleaning system for powdered material processing and storing devices, such as silos, mixers, and dust collectors. In particular, the present invention relates to an automatic interior cleaning system which removes residues from interior surfaces of powdered material devices which process powdered materials.
Examples of powdered materials used in food materials and industrial raw materials currently supplied to the market include granulated sugar, glucose, powdered skim milk, starch, rice bran, seasonings, cement, fly ash, carbon black, salt, detergent, wheat, rice, maize, soybean, malt, quartz sand, aluminum oxide, titanium oxide, calcium carbonate, dust coal, time, soda ash, powdered food mixes, flour, powdered soup, powdered petrochemicals, pharmaceuticals, pigments, mixed fertilizer, phenol resins, polyethylene resins, ABC resins, PVC powder, polypropylene powder, and powder coating. Manufacturing companies produce these powdered materials and pack them in bags or plastic containers to sell. Small and medium scale factories use powdered material straight from the bags or shipping containers. Thus small and medium scale operations do not need large-scale powdered material storage and processing devices.
In contrast, large scale factories use large quantities of powdered materials. The shipping and handling of large quantities of powdered material requires heavy machinery. Typically, air conveyors transport powdered materials from trucks into silos for storage. Pneumatic feeders transport powdered material as needed for processing. Mixers and dust collectors mix and separate powdered materials.
Transporting and processing powdered material stirs up the powdered material. Powdered material accumulates on the interior surfaces of processing devices, such as silos, mixers, and dust collectors. Powdered material is especially prone to adhere to corners. Residues accumulate each time a powdered material processing device is operated. Over time, accumulations of powdered foods spoil. Similarly, powdered chemicals decompose or change in composition. Furthermore, spoiled or chemically-altered powdered material adhering to a ceiling of a processing apparatus falls into and contaminates newly-processed material. Contamination reduces the quality of powdered material. In the worst case, contamination renders powdered material worthless.
A known solution for preventing contamination of powdered material in large-scale operations is to periodically stop production and manually clean the interior of a powder processing device. In general, a worker removes accumulations of powdered materials from interior ceilings, side walls, and processing machinery with an air gun or a high pressure water sprayer.
One problem with manual cleaning is danger to the worker. For example, in a silo, the worker cleans from high places, such as ladders or catwalks. Using a water sprayer on a ladder or a catwalk to clean a silo increases the chances that the worker will slip and fall. Similarly, in mixers and dust collectors, the worker enters the interior of the machinery. Stirring up dust during the cleaning process causes respiratory problems. Also, large accumulations on the ceiling of a processing device can fall and injure or even crush the worker.
Another problem with manual cleaning is contamination of the processing device by the worker. Food-processing devices are particularly susceptible to contamination. The worker introduces bacteria into the interior of the food processing device when the worker enters the device to clean it. Unsanitary conditions result.
A further problem with conventional cleaning methods is down time. Manual cleaning requires stopping the powdered material processing device. Cleaning takes time. Cleaning with water requires additional time for drying. All of the interior processing equipment must be completely dried before restarting the device to prevent coagulation of powdered material. The resulting down time from stopping until restarting increases processing costs of powdered material.
A further problem that occurs with using water to clean powdered material processing devices is waste disposal. Waste water contaminated with powdered material must be properly disposed of. Environmental regulations governing waste water disposal increase the cost and reduce the practicality of using water to clean powdered material processing devices.